Simón Bolívar University

About: Simón Bolívar University is a education organization based out in Caracas, Venezuela. It is known for research contribution in the topics: Population & Crystallization. The organization has 5912 authors who have published 8294 publications receiving 126152 citations.

Indigenous Use of Fire and Forest Loss in Canaima National Park, Venezuela. Assessment of and Tools for Alternative Strategies of Fire Management in Pemón Indigenous Lands

Abstract: In Canaima National Park (CNP), Venezuela, a protected area inhabited by the Pemon people, socio-cultural and demographic changes have contributed to the apparent unsustainable use of fire, leading to forest and habitat loss. This over-use of fire, together with increased forest vulnerability to fire as a result of global climate change, could put both ecosystems and human well-being at risk. The conflict over fire use derives from the fact that whereas the Pemon depend for their livelihood on the use of fire for shifting cultivation and hunting, the policy of the CNP government agencies is fire exclusion (although this is not effectively enforced). Nevertheless, recent ecological studies have revealed that the creation of a mosaic of patches with different fire histories could be used to create firebreaks that reduce the risk of the wildfires that threaten the vulnerable and diverse savanna-forest transition areas. This technique imitates the traditional cooperative savanna burning strategies of the Pemon. By linking research on knowledge systems with management policies, the impasse over fire in the CNP might be avoided.

Matheuristic with machine-learning-based prediction for software-defined mobile metro-core networks

Abstract: In general, humans follow a routine with highly predictable daily movements. For instance, we commute from home to work on a daily basis and visit a selected set of places for commercial and recreational purposes during the nights and weekends. The use of mobile phones increases when commuting via public transportation, during lunch breaks, and at night. Such regular behavior creates predictable spatiotemporal fluctuations of traffic patterns. In this paper, we introduce a matheuristic for dynamic optical routing, which can be implemented as an application into a software-defined mobile carrier network. We use machine learning to predict tidal traffic variations in a mobile metro-core network, which allows us to solve off-line mixed-integer linear programming instances of an optical routing (and wavelength) assignment optimization problem. The optimal results are used to favor near-optimal on-line routing decisions. Results demonstrate the effectiveness of our on-line methodology, with results that match almost perfectly the behavior of a network that performs optical routing reconfiguration with a perfect, oracle-like traffic prediction and the solution of an optimization problem.

Global invasion of Lantana camara: has the climatic niche been conserved across continents?

Abstract: Lantana camara, a native plant from tropical America, is considered one of the most harmful invasive species worldwide. Several studies have identified potentially invasible areas under scenarios of global change, on the assumption that niche is conserved during the invasion process. Recent studies, however, suggest that many invasive plants do not conserve their niches. Using Principal Components Analyses (PCA), we tested the hypothesis of niche conservatism for L. camara by comparing its native niche in South America with its expressed niche in Africa, Australia and India. Using MaxEnt, the estimated niche for the native region was projected onto each invaded region to generate potential distributions there. Our results demonstrate that while L. camara occupied subsets of its original native niche in Africa and Australia, in India its niche shifted significantly. There, 34% of the occurrences were detected in warmer habitats nonexistent in its native range. The estimated niche for India was also projected onto Africa and Australia to identify other vulnerable areas predicted from the observed niche shift detected in India. As a result, new potentially invasible areas were identified in central Africa and southern Australia. Our findings do not support the hypothesis of niche conservatism for the invasion of L. camara. The mechanisms that allow this species to expand its niche need to be investigated in order to improve our capacity to predict long-term geographic changes in the face of global climatic changes.

Driving Missing Data at Next-to-Leading Order

Abstract: The prediction of backgrounds to new physics signals in topologies with large missing transverse energy and jets is important to new physics searches at the LHC. Following a CMS study, we investigate theoretical issues in using measurements of +2-jet production to predict the irreducible background to searches for missing energy plus two jets that originates from Z + 2-jet production where the Z boson decays to neutrinos. We compute ratios of + 2-jet to Z + 2-jet production ˜¯ ˜